You're citing articles from August, which were before Zuckerberg's decision not to sell any this year, so the info is probably out-of-date.
Here's an official source - FB's latest 10-Q: http://www.sec.gov/Archives/edgar/data/1326801/000132680112000006/fb-9302012x10q.htm
"November 14, 2012 - approximately 773 million outstanding shares and approximately 31 million net-settled Pre-2011 RSUs not held by then-current employees as of October 15, 2012"
Here's an official source - FB's latest 10-Q: http://www.sec.gov/Archives/edgar/data/1326801/000132680112000006/fb-9302012x10q.htm
"November 14, 2012 - approximately 773 million outstanding shares and approximately 31 million net-settled Pre-2011 RSUs not held by then-current employees as of October 15, 2012"